Fixed gear versus single speed
A single speed bike has one gear, but you can freewheel. A fixie has one gear and you cannot freewheel. The pedals are locked to the rear wheel by a threaded cog. When the wheel turns, the pedals turn. When you stop pedalling, the wheel stops driving.
Most fixies in the UK have a flip-flop rear hub, with a fixed cog on one side and a single speed freewheel on the other. Swap the wheel around and you have a single speed freewheel bike for commuting, or a true fixed-gear for rides where you want the direct connection to the rear wheel. A flip-flop hub is the most practical setup for most riders.
A true fixed-gear has a learning curve. The pedals never stop turning as long as the bike is moving. Brake by resisting the pedals as well as using the front brake. Think ahead about gear ratios, gradients, and junctions. The reward is a feel for the bike that no geared system can match.
Prices on the used market
Under two hundred and fifty pounds you are in entry-level territory. Charge Plug, Fuji Track, older Mongoose Cachet. Aluminium or basic steel frames, flip-flop rear hubs, reasonable components. Good first fixie for a newer rider.
Two hundred and fifty to five hundred pounds buys quality used fixies. Condor Pista, newer Fuji Feather, Brother Kopek, State Bicycle Co. Most bikes in this range are well made, have decent wheels, and are built for road use with at least a front brake fitted.
Five hundred to a thousand pounds is where proper steel frame fixies sit. Mercian, Bob Jackson, Holdsworth, Rourke. Hand-built British steel frames with full build kits. These are often sold by riders moving on rather than bikes that have been ridden into the ground.
Above a thousand pounds you are into premium territory. Cinelli Vigorelli, older Cervelo T4 rebuilt for road use, high-end Condor models, carbon track bikes adapted for the road. Unusual specs and custom builds become common above this price point.
Brands worth knowing
Condor, based in London, has been making fixies for decades. The Pista is their classic and a favourite among UK cycle couriers. British made, well supported, and worth the premium.
Fuji makes the Track and the Feather at accessible prices. Both are well-regarded starter fixies, with steel frames that punch above their price. Used Fuji fixies are plentiful and easy to find.